If you want to gain RP XP during crafting, have a friend come with you and talk with them.
I think this was the idea behind consolidating the crafting stations under one roof.
The only craft I know enough about to make an informed comment is potions--which I'm happy did not get consolidated, though I wish there was a herbalism station around Degannwy. (Where are the Elves making all those barkskin potions? Maybe there is one, and I just haven't found it!)
Anyway, I've never found *any* PCs in the Vallaki crafting hall. I've gone there several times specifically to find crafters and give them my business in game, but each time it was just the NPCs. Perhaps some sort of solution to Dark Dreams' request could be worked out by tweaking that area.
One idea: Have in the hall a station that allows crafters to trade unwanted "practice" items for tiny experience awards. That way it would be difficult to power level because it would be in only one location (that could be monitored and controlled for exploits) and limited by how much raw material a character had and how much the character could carry.
*Second* it would encourage traffic in the hall and thus make roleplay among crafters and customers more likely.